SEARCH FOR ANTIBIOTICS: SCREENIXCi PROGRAMS 



23 



containing monocytes are confronted with 

 the antibiotic or the culture filtrate to be 

 studied. If the antibiotic is active intra- 

 cellularly, the brucellae are killed; if not, 

 their life is detected by the formation of 

 bacterial colonies when the monocytes are 

 flooded with agar. 



Among the special techniques, it is suf- 

 ficient to mention those devised for the 

 study of antagonists active against plant 

 pathogens (Cooper and Chilton, 1949; Stessel 

 (•t al., 1953). The actinomycetes attracted 

 particular attention because of the early 

 observations by KenKnight (1941) and 

 Alexopoulos (1941), among others, that they 

 were active upon the potato scab organism 

 and other plant pathogens. 



Screening Surveys 



Numerous surveys Xvcwe shown that 

 actinomycetes capable of producing anti- 

 biotics in vitro are widely distributed in 

 nature. They are the most common anti- 

 biotic-producers that can be isolated from 

 soil (Waksman and Lechevalier, 1901). 



.1 ntimicrobial Surreys 



Among the previous surveys, in addition 

 to those already listed, it is sufficient to m(Mi- 

 tion those of Borodulina (1935), Burkholder 

 (194(3), Waksman et al. (1946), Landerkin 

 and Lochhead (1950), Harris and Ruger 

 (1953), and Craven et al. (1960). A sum- 

 mary of some of l^oth older and more recent 

 surveys is shown in Table 2. As can be seen, 



Table 2 

 Surveys of antagonistic activity of actinomycetes 



* Antagonistic to Colletotrichum gloeosporioides. 

 t Antagonistic to Pythinm arrhenomanes. 



